Liquid circulation type cooling system

ABSTRACT

A liquid circulation type cooling system includes a circulating pump for circulating a liquid, a heat exchanger disposed in a heat radiation space and for radiating heat outside the system. The heat exchanger contains a core unit, a liquid reservoir for storing the liquid positioned on the upstream side of the core unit and having a liquid opening, another liquid reservoir for storing the liquid and positioned on the downstream side of the core unit, the other liquid reservoir having a liquid opening, a heat-receiving member, a piping, and a fan for supplying air to the heat exchanger to effect forced air-cooling.

The present application is based on Japanese patent application No.2004-033761, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid circulation type coolingsystem wherein a liquid is circulated in the system to transfer heatgenerated from a heat-generating element to a heat radiation space bymeans of the liquid thereby to radiate the heat, and particularly to aliquid circulation type cooling system mounted on an electronicinstrument which may be positioned in the upside-down postures as aresult of mounting the cooling system.

2. Description of the Related Art

In recent years, high-performance electronic instruments have beendeveloped, so that a heat-generating amount of, particularly, circuitparts such as CPU (Central Processing Unit) and electric power unitcontained in a main body increases. In this connection, improvements inheat radiation to the outside are desired.

As a means for promoting heat radiation of a heat-generating element, acooling device wherein a radiator made of a metal excellent in thermalconductivity is attached to a heat-generating element such as CPU, andthe radiator is air-cooled is known. However, a cooling device of anair-cooling type requires a heat radiation area for a radiator inresponse to an amount of heat radiation, resulting in a disadvantage ofincreasing a size of the cooling device. Besides, there is recently sucha tendency that a heat-generating amount of a CPU increases accompaniedwith high-speed processability and multifunctionality required forelectronic instruments. In this respect, heat radiation performancereaches substantially a limit in a cooling device of an air-coolingtype.

For improving such poor heat radiation, a liquid circulation typecooling system wherein a heat transfer medium such as a coolant is usedis known (for example, see Japanese patent application laid-open No.2003-209210 (FIG. 2)).

FIG. 1 is a schematic diagram showing a circuit of a conventional liquidcirculation type cooling system wherein the liquid circulation typecooling system 50 includes a circulating pump 51 for circulating aliquid, a heat-receiving member 53 attached to an element to be cooledsuch as a heat-generating element, the heat-receiving member beingserved for transferring efficiently heat from the element to be cooledto the liquid, a radiator 52 for radiating heat outside a casing of aninstrument and disposed in a heat-radiating space, a liquid reservoir 56positioned at the upper part of the radiator 52 and storing thecirculating liquid, a header 57 positioned at the bottom of the radiator52, a piping 54 for connecting respective components with each other andmade of a flexible tube or a fixed piping, and a fan 55 for supplyingwind to the radiator 52 to perform forced air-cooling.

In the liquid circulation type cooling system 50, when the circulatingpump 51 is driven, a liquid is circulated in the circulating circuit,whereby heat generated from an element to be cooled such as aheat-generating element is received by the heat-receiving member 53 totransfer the heat to the liquid. The heat thus transferred is deliveredto the radiator 52 by means of the circulating liquid, and the heatedliquid is forcibly air-cooled by the fan 55 to radiate the heat.

In the above-described liquid circulation type cooling system 50, theliquid reservoir 56 is provided for such a purpose that an amount ofliquid is kept constant in the system with taking permeation of theliquid from connecting sections and surfaces of respective componentsinto consideration. In this connection, the cooling system 50 isrequired to have a sealed structure for preventing leakage of the liquidin the case when the cooling system is positioned close to electronicinstruments. However, pressure changes appear dependent upon temperaturechanges in the system, if the cooling system has a sealed structure.Particularly, since a pressure increases as a result of a temperaturerise of the liquid, the liquid reservoir 56 contains not only the liquid56A, but also an air layer 56B so as to be capable of responding topressure increase. Furthermore, when air enters in the circulating pump51, the radiator 52, or the heat-receiving member 53, performance of thecooling system decreases remarkably, and thus, a position of the liquidreservoir 56 is usually kept at the highest position of the system.

In this respect, however, when a setting condition of an electronicinstrument in use is fixed, it is possible to maintain always a positionof the liquid reservoir 56 at the highest position in the instrument.When a setting posture of an electronic instrument is changed due tousability in a user, in other words, when the electronic instrument ispositioned upside-down, the liquid reservoir 56 is positioned at thelowest part of the instrument.

FIG. 2 is a schematic diagram showing a circuit in the case when theliquid circulation type cooling system 50 of FIG. 1 is positionedupside-down wherein the header 57 is positioned at the top of theradiator 52, and a liquid flows from the radiator 52 in a direction tothe circulating pump 51 through the header 57. However, since the airlayer 57B resides in the upper part of the liquid 57A in the header 57,the air flows also into the piping 54 when the liquid flows into thepiping 54 positioned on the downstream side of the header 57. If the airenters into the piping 54, circulating performance of the liquiddecreases, and as a result, a circulating function of the systemdecreases remarkably.

There is a “projector” as an example of a case where a setting positionof an electronic instrument is positioned upside-down in use. As to suchprojector, there is either a case where it is used in a floorstandingposition, or a case where it is mounted to a ceiling for use.Accordingly, when a liquid circulation type cooling system is mounted ona “projector”, it is required to respond to such changes in a posture(upside-down positions) of the projector applied.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aliquid circulation type cooling system which is mounted to an electronicinstrument, whereby the electronic instrument can be positioned in theupside-down postures.

In order to achieve the above-described object, a liquid circulationtype cooling system according to the present invention comprises amember for receiving heat from a heat-generating element such as asemiconductor element; a reservoir for containing liquid to transferheat; a radiator for radiating heat which is transferred through theliquid from the member; and a system for circulating the liquid amongthe reservoir, the radiator and the member wherein the radiatorcomprises a heat exchanger and a fan for forcibly supplying air to theheat exchanger.

In the liquid circulation type cooling system of the present invention,the reservoir functions as a header for supplying the liquid to a coreunit of the heat exchanger.

In the liquid circulation type cooling system of the present invention,the cooling system operates even in the upside-down installationposture.

Furthermore, a liquid circulation type cooling system according to thepresent invention comprises a heat radiation space for radiating heat ofliquid heated by a heat-generating element; and a system for circulatingthe liquid through the heat radiation space; the heat radiation spacecomprising a first liquid reservoir on a first side thereof; a secondliquid reservoir on a second side thereof to be in series with the firstliquid reservoir; the first and second liquid reservoir being verticallyarranged at different levels; and liquid openings provided on the firstand second liquid reservoirs to be connected to the liquid-circulatingsystem wherein the liquid opening of the first liquid reservoir isfilled with the liquid, even if the first liquid reservoir is positionedat an upper place than that of the second liquid reservoir, while theliquid opening of the second liquid reservoir is filled with the liquid,even if the second liquid reservoir is positioned at the upper placethan that of the first liquid reservoir.

In the liquid circulation type cooling system of the present invention,the heat radiation space comprises a core unit provided between thefirst and second liquid reservoirs to be connected therethrough, therebyproviding a heat exchanger.

Moreover, a liquid circulation type cooling system according to thepresent invention comprises a heat radiation space for radiating heat ofliquid heated by a heat-generating element; and a system for circulatingthe liquid through the heat radiation space; the heat radiation spacecomprising a first liquid reservoir on a first side thereof; a secondliquid reservoir on a second side thereof to be in series with the firstliquid reservoir; the first and second liquid reservoirs beinghorizontally arranged at the same level; and liquid openings provided onthe first and second liquid reservoirs to be connected to theliquid-circulating system wherein the liquid openings of the first andsecond liquid reservoirs are filled with the liquid, even if the coolingsystem is installed in the upside-down postures.

In the liquid circulation type cooling system of the present invention,the heat radiation space comprises a core unit provided between thefirst and second liquid reservoirs to be connected therethrough, therebyproviding a heat exchanger.

In the liquid circulation type cooling system of the present invention,the heat exchanger has “corrugated straight fin core” type structurewhich comprises tubes, fins, and headers, the headers being served forthe liquid reservoirs.

In the liquid circulation type cooling system of the present invention,a fan for supplying air to forcibly cool the heat exchanger is disposedoutside the heat exchanger.

In the liquid circulation type cooling system of the present invention,the liquid reservoir is provided with a liquid level sensor forgenerating a warning signal in case of shortage of the liquid.

According to the liquid circulation type cooling system of the presentinvention, the liquid reservoirs each for storing a liquid are disposedon the upstream and the downstream sides of the heat radiation space,respectively, and at least the liquid opening of the liquid reservoirpositioned at the downstream side is filled always with the liquid.Thus, even if the liquid circulation type cooling system is positionedin the upside-down postures, it is possible to prevent that air flowsinto the system other than the liquid reservoir. As a result, electronicinstruments may be positioned in the upside-down postures, so that anapplicable scope for the liquid circulation type cooling system can bebroadened.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be explained in more detail in conjunctionwith appended drawings, wherein:

FIG. 1 is a schematic diagram showing a circuit of a conventional liquidcirculation type cooling system;

FIG. 2 is a schematic diagram showing a circuit of the conventionalliquid circulation type cooling system which is positioned upside-down;

FIG. 3 is a schematic diagram showing a circuit of a liquid circulationtype cooling system according to a first embodiment of the presentinvention;

FIG. 4A is an enlarged side view showing a heat exchanger used in theliquid circulation type cooling system according to the first embodimentof the present invention;

FIG. 4B is an enlarged front view showing the heat exchanger of FIG. 4A;

FIG. 5 is a schematic diagram showing a circuit of the liquidcirculation type cooling system according to the first embodiment of thepresent invention which is positioned upside-down;

FIG. 6 is a schematic diagram showing a circuit of a liquid circulationtype cooling system according to a second embodiment of the presentinvention;

FIG. 7A is an enlarged side view showing a heat exchanger used in theliquid circulation type cooling system according to the secondembodiment of the present invention;

FIG. 7B is an enlarged front view showing the heat exchanger of FIG. 7A;

FIG. 8 is a schematic diagram showing a circuit of the liquidcirculation type cooling system according to the second embodiment ofthe present invention which is positioned upside-down;

FIG. 9A is an enlarged side view showing a heat exchanger used in theliquid circulation type cooling system according to the third embodimentof the present invention; and

FIG. 9B is an enlarged plan view showing the heat exchanger of FIG. 9A

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described indetail hereinafter by referring to the accompanying drawings.

First Embodiment

FIG. 3 is a schematic diagram showing a circuit of a liquid circulationtype cooling system according to a first embodiment of the presentinvention wherein the liquid circulation type cooling system 10 includesa circulating pump 11 for circulating a liquid such as water, a heatexchanger 12 for radiating heat outside a casing for the system, theheat exchanger being disposed in a heat radiation space, aheat-receiving member 13 attached to an element to be cooled such as aheat-generating element, the heat-receiving member being served fortransferring efficiently heat from the element to be cooled to theliquid, a piping 14 for connecting the above-mentioned components witheach other, the piping being composed of a flexible tube or a fixedpiping, and a fan 15 for supplying air to the heat exchanger 12 toachieve forced-air cooling.

The heat exchanger 12 has a core unit 18, a liquid reservoir 16 formedat the top of the core unit 18 in the vertical direction in the drawing,and another liquid reservoir 17 formed at the bottom of the core unit 18in the drawing. The core unit 18, and the liquid reservoirs 16 and 17are incorporated into one member. The liquid reservoir 16 containsinside the tank a space of the same capacity as that of the liquidreservoir 17, and vice versa. The whole space inside the liquidreservoir 17 is filled with a liquid, while the liquid reservoir 16contains a liquid layer 16A and an air layer 16B.

FIG. 4A is an enlarged side view showing the heat exchanger 12, and FIG.4B is an enlarged front view showing the heat exchanger 12 wherein theheat exchanger 12 is the one having a “corrugated straight fin core”type structure, which is composed of a core unit 18, a liquid reservoir16 positioned at the top of the core unit 18 in the drawing, and theother liquid reservoir 17 positioned at the bottom of the core unit 18.

The core unit 18 is in a “corrugated straight fin core” which isobtained by incorporation of frill-shaped fins 121 made from a metalsuch as aluminum excellent in heat radiation with flat tubes 122 madefrom a metal such as aluminum by means of brazing.

Furthermore, in a heat exchanger of “corrugated straight fin core” typestructure, both upper and lower headers are used for serving the liquidreservoirs 16 and 17 each of which is formed into a size having acapacity required for functioning as a liquid reservoir.

The liquid reservoir 16 has inside the tank a space of the same capacityas that of the liquid reservoir 17, and vice versa. Furthermore, aliquid opening 123 into and from which a liquid may be introduced anddischarged is provided on the bottom side of the liquid reservoir 16,while a same liquid opening 124 is also provided on the upper side ofthe liquid reservoir 17. The liquid opening 123 may be connected to theliquid opening 124 through the piping 14 shown in FIG. 3.

Moreover, the liquid reservoir 16 is provided with aninjection/degasification nozzle 125 on a side thereof, theinjection/degasification nozzle 125 being served for injecting a liquidinto the liquid reservoir and regulating a pressure of air in the liquidreservoir 16.

An internal capacity of the liquid reservoir 16 and that of the liquidreservoir 17 are decided on the basis of a volume of the whole system,an amount of air for adjusting an amount of increasing internal pressureaccompanied with an increasing volume in case of rising a liquidtemperature, and a losing amount of a liquid component (a permeationamount of a liquid) in the whole system. It is to be noted that theinjection/degasification nozzle 125 is closed except for the case wherea liquid is injected.

In the following, operations of the liquid circulation type coolingsystem 10 will be described by referring to FIGS. 3, 4A, and 4B.

In FIG. 3, first, when the liquid circulating pump 11 is driven, aliquid filled in a liquid circulation system is forcibly delivered. Theheat-receiving member 13 is served for transferring heat conductedthermally from a heat-generating element being an element to be cooledto the liquid. Then, the liquid is forcibly delivered to the heatexchanger 12 through the piping 14. As shown in FIG. 4A, when the liquidis introduced from the liquid opening 123 provided on the liquidreservoir 16 in the heat exchanger 12, the liquid passes through thecore unit 18 from the liquid reservoir 16. In the core unit 18, heat isradiated from the fins 121 incorporated with the tubes 122 in the casewhere the liquid passes through the tubes 122 as shown in FIG. 4B. Airis introduced into the heat exchanger 12 by means of the fan 15 (seeFIG. 3) to promote heat radiation in the fins 121.

On one hand, the liquid transferred to the liquid reservoir 17 goes outfrom the liquid opening 124, and is transferred to the liquidcirculating pump 11 through the piping 14 (see FIG. 3). In such a seriesof flow, an internal pressure increases in the liquid circulation systemdue to a temperature rise in the case when the liquid receives a heatfrom the element to be cooled. In such a case, however, an amount ofincreasing pressure is absorbed by an air layer 16B in the liquidreservoir 16 as a bumper.

Then, operations of the liquid circulation type cooling system 10 in thecase where the cooling system is positioned upside-down are described byreferring to FIG. 5.

FIG. 5 is a schematic diagram showing a circuit of the liquidcirculation type cooling system 10 according to the first embodiment ofthe present invention in the case where it is positioned in theupside-down posture. In this situation, when the liquid circulating pump11 is driven, the liquid filled in the liquid circulation system isforcibly delivered in the directions indicated by the arrows, and heatderived from a heat-generating element being an element to be cooled isconducted thermally to the liquid in the heat-receiving member 13. Theliquid is forcibly delivered to the liquid reservoir 16 in the heatexchanger 12 through the piping 14, the heat is radiated from theliquid, when the liquid passes through the core unit 18, and then, theliquid is transferred to the liquid circulating pump 11 from the liquidreservoir 17.

As mentioned above, in FIG. 5, the liquid reservoir 17 is positioned atthe head of the core unit 18, and the liquid is introduced to thecirculating pump 11 from the core unit 18 through the liquid reservoir17. In this situation, an air layer 17B resides over a liquid layer 17Ain the liquid reservoir 17. In this respect, since a discharge port (theliquid opening 124 in FIGS. 4A and 4B) for liquid is filled with theliquid, no air flows into the piping 14 in the case when the liquidflows into the piping 14 in the downstream side of the liquid reservoir17. Accordingly, air does not put in the liquid in the piping 14, evenif the liquid circulation type cooling system 10 is positionedupside-down, so that decrease in a flow rate, stoppage of a pump and thelike due to decrease in circulation of liquid can be prevented.

According to the liquid circulation type cooling system 10 of theabove-mentioned first embodiment, the following advantageous effects canbe obtained.

(1) The liquid opening 123 is provided on the side to which the coreunit 18 is connected in the liquid reservoir 16, while the liquidopening 124 is provided on the side to which the core unit 18 isconnected in the liquid reservoir 17. In this situation, even when anelectronic instrument on which the liquid circulation type coolingsystem is mounted is positioned in the upside-down postures, the liquidopenings 123 and 124 are always filled with a liquid, so that no airenters in the liquid in the piping 14. Thus, decrease in a flow rate,stoppage of a pump and the like due to decrease in circulation of liquidcan be prevented.

(2) A heat exchanger having a “corrugated straight fine core” typestructure is used for the heat exchanger of the invention, so that theupper and lower header sections of which are served for liquidreservoirs, respectively. Accordingly, the tubes 122 are always filledwith a coolant, even if a plurality of liquid reservoirs is not disposedin an individual opposed part. For this reason, a structure of a liquidcirculation circuit can be simplified, whereby increase in parts to beprovided and increase in a space for mounting a liquid circulation typecooling system can be suppressed, and thus, downsizing and costreduction of electronic instruments can be realized while ensuring goodheat radiation.

(3) Since the air layer 16B resides in the liquid reservoir 16 or theair layer 17B resides in the liquid reservoir 17 for canceling anincreasing amount of pressure in the liquid circulation system, increasein pressure derived from temperature changes of a liquid contained inthe liquid circulation system can be absorbed.

Second Embodiment

FIG. 6 is a schematic diagram showing a circuit of a liquid circulationtype cooling system according to a second embodiment of the presentinvention wherein the liquid circulation type cooling system 20 includesa circulating pump 21, for circulating a liquid, a heat exchanger 22 forradiating heat outside a casing for the system, the heat exchanger beingdisposed in a heat radiation space, a heat-receiving member 23 attachedto an element to be cooled such as a heat-generating element, theheat-receiving member being served for transferring efficiently heatfrom the element to be cooled to the liquid, a piping 24 for connectingthe above-mentioned components with each other, the piping beingcomposed of a flexible tube or a fixed piping, and a fan 25 forsupplying wind to the heat exchanger 22 to achieve forced-air cooling.

The heat exchanger 22 has a core unit 18, a liquid reservoir 26 formedon the left side with respect to the core unit 18 in the drawing, andanother liquid reservoir 27 formed on the right side to the core unit 18in the drawing. The core unit 18, and the liquid reservoirs 26 and 27are incorporated into one member. The liquid reservoir 26 containsinside the tank a space of the same capacity as that of the liquidreservoir 27, and vice versa. The liquid reservoir 26 contains a liquidlayer 26A and an air layer 26B, while the liquid reservoir 27 contains aliquid layer 27A and an air layer 27B.

FIG. 7A is an enlarged side view showing the heat exchanger 22, and FIG.7B is an enlarged plan view showing the heat exchanger 22 wherein theheat exchanger 22 is the one having a “corrugated straight fin core”type structure, which is composed of a core unit 18, a liquid reservoir26 positioned on the left side to the core unit 18 in the drawing, andthe other liquid reservoir 27 positioned on the right side to the coreunit 18.

The core unit 18 is the one formed by the same manner as that of theliquid circulation type cooling system 10 in the first embodiment.

The liquid reservoir 26 has inside the tank a space of the same capacityas that of the liquid reservoir 27, and vice versa. Furthermore, aliquid opening 223 into and from which a liquid may be introduced anddischarged is provided on the liquid reservoir 26 on the right side ofthe core unit 18, while a same liquid opening 224 is provided on theliquid reservoir 27 on the left side of the core unit 18. The liquidopening 223 may be connected to the liquid opening 224 through thepiping 24 shown in FIG. 6.

Moreover, the liquid reservoir 26 is provided with aninjection/degasification nozzle 225 on a side thereof, theinjection/degasification nozzle 225 being served for injecting a liquidinto the liquid reservoir 26 and regulating a pressure of air in theliquid reservoir 26.

In the following, operations of the liquid circulation type coolingsystem 20 will be described by referring to FIG. 6 and FIGS. 7A, 7B.

In FIG. 6, first, when the liquid circulating pump 21 is driven, aliquid filled in the liquid circulation system is forcibly delivered.The heat-receiving member 23 is served for transferring heat conductedthermally from a heat-generating element being an element to be cooledto the liquid. Then, the liquid is forcibly delivered to the heatexchanger 22 through the piping 14. As shown in FIG. 7A, when the liquidis introduced from the liquid opening 224 provided on the liquidreservoir 27 in the heat exchanger 22, the liquid passes through thecore unit 18 from the liquid reservoir 27. In the core unit 18, heat isradiated from the fins 121 incorporated with the tubes 122, when theliquid passes through the tubes 122 as shown in FIG. 7B. Air isintroduced into the heat exchanger 22 by means of the fan 25 (see FIG.6) to promote heat radiation in the fins 121.

On one hand, the liquid transferred to the liquid reservoir 26 goes outfrom the liquid opening 223, and is transferred to the liquidcirculating pump 21 through the piping 24 (see FIG. 6).

Then, operations of the liquid circulation type cooling system 20 in thecase where the cooling system is positioned in the upside-down postureare described by referring to FIG. 8.

FIG. 8 is a schematic diagram showing a circuit of the liquidcirculation type cooling system 20 according to the second embodiment ofthe present invention in the case where it is positioned upside-down. Inthis situation, when the liquid circulating pump 21 is driven, theliquid filled in the liquid circulation system is forcibly delivered inthe directions indicated by the arrows, and heat derived from aheat-generating element being an element to be cooled is conductedthermally to the liquid in the heat-receiving member 23. The liquid isforcibly delivered to the liquid reservoir 27 in the heat exchanger 22through the piping 24, the heat is radiated from the liquid, when theliquid passes through the core unit 18, and then, the liquid istransferred to the liquid circulating pump 21 from the liquid reservoir26.

As mentioned above, the liquid is introduced to the circulating pump 21from the core unit 18 through the liquid reservoir 26 in FIG. 8. In thissituation, an air layer 26C resides over the liquid layer 26A in theliquid reservoir 26. In this respect, since a discharge port (the liquidopening 223 in FIGS. 7A and 7B) for liquid is filled with the liquid, noair flows into the piping 24 in the case when the liquid flows into thepiping 24 in the downstream side of the liquid reservoir 26.Accordingly, air does not put in the liquid in the piping 24, even ifthe liquid circulation type cooling system 20 is positioned upside-down,so that decrease in a flow rate, stoppage of a pump and the like due todecrease in circulation of liquid can be prevented.

According to the above-mentioned liquid circulation type cooling system20 of the second embodiment, the same advantageous effects as that ofthe liquid circulation type cooling system 10 of the first embodimentcan be obtained.

Third Embodiment

FIG. 9A is a side view showing a structure of a heat exchanger 32 usedin a liquid circulation type cooling system according to a thirdembodiment of the present invention, and FIG. 9B is a plan view showingthe heat exchanger 32 wherein the heat exchanger 32 is the one having a“corrugated straight fin core” type structure, which is composed of acore unit 18, a liquid reservoir 36 positioned on the left side to thecore unit 18 in the drawing, and another liquid reservoir 37 positionedon the right side to the core unit 18.

The heat exchanger 32 has the same structure as that of the heatexchanger 22 except that the liquid reservoir 36 has a liquid opening323 into and from which a liquid may be introduced and discharged on aside of the liquid reservoir 36 perpendicular to the side to which thecore unit 18 is connected, while a liquid opening 324 which is the sameas the liquid opening 323 is provided on a side of the liquid reservoir37 perpendicular to the side to which the core unit 18 is connectedwherein the side of the liquid opening 324 is in a direction opposite tothe liquid opening 323, and the liquid reservoir 36 is provided with aninjection/degasification nozzle 325 on the top side thereof. Theinjection/degasification nozzle 325 is served for injecting a liquidinto the liquid reservoir and regulating a pressure of air in the liquidreservoir 36.

When the heat exchanger 32 is used in place of the heat exchanger 22 inthe liquid circulation type cooling system 20 shown in FIG. 6, the sameadvantageous effects as that of the liquid circulation type coolingsystem 20 according to the second embodiment can be achieved in thepresent embodiment.

While a heat exchanger contains two liquid reservoirs in theabove-described embodiments, the heat exchanger may contain three ormore liquid reservoirs. Furthermore, although a structure wherein a coreunit 18 is formed into a single layer with respect to a direction alongwhich air passes through has been described, two or more layers may beapplied in response to an amount of heat radiation. Moreover, liquidreservoirs for a coolant have not been separately disposed in a liquidcirculation system, but such liquid reservoirs may be individuallydisposed in a liquid circulation system.

In addition, it may be arranged in such that when a coolant in a liquidreservoir decreases, an alarm signal is given by attaching a liquidlevel sensor to the liquid reservoir.

It will be appreciated by those of ordinary skill in the art that thepresent invention can be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof.

The presently disclosed embodiments are therefore considered in allrespects to be illustrative and not restrictive. The scope of theinvention is indicated by the appended claims rather than the foregoingdescription, and all changes that come within the meaning and range ofequivalents thereof are intended to be embraced therein.

1. A liquid circulation type cooling system, comprising: a member forreceiving heat from a heat-generating element such as a semiconductorelement; a reservoir for containing liquid to transfer heat; a radiatorfor radiating heat which is transferred through the liquid from themember; and a system for circulating the liquid among the reservoir, theradiator and the member, wherein the radiator comprises a heat exchangerand a fan for forcibly supplying air to the heat exchanger.
 2. Theliquid circulation type cooling system as defined in claim 1, wherein:the reservoir functions as a header for supplying the liquid to a coreunit of the heat exchanger.
 3. The liquid circulation type coolingsystem as defined in claim 1, wherein: the cooling system operates evenin the upside-down installation posture.
 4. A liquid circulation typecooling system, comprising: a heat radiation space for radiating heat ofliquid heated by a heat-generating element; and a system for circulatingthe liquid through the heat radiation space; the heat radiation spacecomprising a first liquid reservoir on a first side thereof; a secondliquid reservoir on a second side thereof to be in series with the firstliquid reservoir; the first and second liquid reservoir being verticallyarranged at different levels; and liquid openings provided on the firstand second liquid reservoirs to be connected to the-liquid-circulatingsystem; wherein the liquid opening of the first liquid reservoir isfilled with the liquid, even if the first liquid reservoir is positionedat an upper place than that of the second liquid reservoir, while theliquid opening of the second liquid reservoir is filled with the liquid,even if the second liquid reservoir is positioned at the upper placethan that of the first liquid reservoir.
 5. The liquid circulation typecooling system as defined in claim 4, wherein: the heat radiation spacecomprises a core unit provided between the first and second liquidreservoirs to be connected therethrough, thereby providing a heatexchanger.
 6. A liquid circulation type cooling system, comprising: aheat radiation space for radiating heat of liquid heated by aheat-generating element; and a system for circulating the liquid throughthe heat radiation space; the heat radiation space comprising a firstliquid reservoir on a first side thereof; a second liquid reservoir on asecond side thereof to be in series with the first liquid reservoir; thefirst and second liquid reservoirs being horizontally arranged at thesame level; and liquid openings provided on the first and second liquidreservoirs to be connected to the liquid-circulating system; wherein theliquid openings of the first and second liquid reservoirs are filledwith the liquid, even if the cooling system is installed in theupside-down postures.
 7. The liquid circulation type cooling system asdefined in claim 6, wherein: the heat radiation space comprises a coreunit provided between the first and second liquid reservoirs to beconnected therethrough, thereby providing a heat exchanger.
 8. Theliquid circulation type cooling system as defined in claim 5, wherein:the heat exchanger has “corrugated straight fin core” type structurewhich comprises tubes, fins, and headers, the headers being served forthe liquid reservoirs.
 9. The liquid circulation type cooling system asdefined in claim 7, wherein: the heat exchanger has “corrugated straightfin core” type structure which comprises tubes, fins, and headers, theheaders being served for the liquid reservoirs.
 10. The liquidcirculation type cooling system as defined in claim 5, wherein: a fanfor supplying air to forcibly cool the heat exchanger is disposedoutside the heat exchanger.
 11. The liquid circulation type coolingsystem as defined in claim 7, wherein: a fan for supplying air toforcibly cool the heat exchanger is disposed outside the heat exchanger.12. The liquid circulation type cooling system as defined in claim 4,wherein: the liquid reservoir is provided with a liquid level sensor forgenerating a warning signal in case of shortage of the liquid.
 13. Theliquid circulation type cooling system as defined in claim 6, wherein:the liquid reservoir is provided with a liquid level sensor forgenerating a warning signal in case of shortage of the liquid.